1. Technical Field
The present invention generally relates to audio processing. More specifically, the present invention relates to enhancing a monaural audio signal.
2. Description of Related Art
Presently, there are numerous methods for reducing background noise from speech in adverse environments. Many of these methods require multiple microphones. Techniques such as beam-forming, time-difference-of-arrival, inter-microphone level differences, and blind source separation are used to spatially filter signals from the multiple microphones to suppress noise originating from different spatial locations relative to a location of a wanted signal, such as speech.
There are also some methods for using a monaural signal to reducing background noise. For example, a noise suppressor is sometimes incorporated into speech codecs or within a telecommunications network. In these cases, the noise suppressor is commonly used to suppress only stationary or slowly time-varying background noise.
Disadvantageously, in adverse environments containing non-stationary noise, noise leakage and audio artifacts can result when using the noise suppressor. Additionally, noise originating in close proximity to a speech source may not be distinguishable from the speech source using method using the multiple microphones. Furthermore, damage to, blockage of, or mismatch between the multiple microphones may result in suboptimal performance. In these cases, a system using the multiple microphones may revert to a monaural method for noise suppression. As such, it is advantageous to have a system which may provide non-stationary noise suppression using the monaural signal, such as provided by a single microphone.